Obstructive sleep apnea affects approximately 2-4% of middle-aged adults in the general population and is associated with several medical conditions including hypertension and coronary artery. Research over the last decade has shown that obstructive sleep apnea may also increase the propensity for insulin resistance, glucose intolerance, and type 2 diabetes mellitus. Positive airway pressure (PAP) is the first line therapy for the treatment of obstructive sleep apnea. While PAP therapy has several favorable effects such as improvements in daytime sleepiness and quality of life, it is not clear whether using PAP therapy can alter metabolic risk. The overall objective of this study is to examine whether treatment of obstructive sleep apnea with positive airway pressure therapy improves glucose tolerance and insulin sensitivity. The primary hypothesis of this study is that PAP therapy of obstructive sleep apnea will improve in insulin sensitivity and glucose metabolism.

Insulin sensitivity will be determined with the insulin-modified frequently sampled intravenous glucose tolerance test (IVGTT) before and 2-months after study intervention. This test requires administration of a weight-adjusted dose of D50W as an IV bolus at time "zero". After the glucose bolus, blood samples are drawn at the scheduled times for 3-hours. At the 20-minute mark, a weight-adjusted dose of regular insulin is administered. The resulting serum is analyzed for glucose and insulin and the "minimal model" (MINMOD) will be used to derive insulin sensitivity.

Glucose effectiveness is the ability for glucose to move intracellularly in the absence of insulin. It is a parameter that results from the MINMOD analysis of the serum glucose and insulin levels derived from the frequently sampled intravenous glucose tolerance test.

The disposition index is the mathematical product of insulin sensitivity (SI) and acute insulin response to glucose (AIRG) both of which are derived from the MINMOD analysis of the frequently sampled intravenous glucose tolerance test data.

Results of the oral glucose tolerance test will be analyzed using indices derived from the serial glucose and insulin levels over the 2 hour period. Examples include areas under the glucose and insulin curves and glucose tolerance status (normal, impaired, diabetic)

Positive airway pressure(PAP) therapy is the standard of care for patients with obstructive sleep apnea. During sleep, a mask is worn over the nose and connected to the PAP machine.

Device: Positive Pressure Therapy (PAP)

Positive pressure therapy is the standard of care for managing obstructive sleep apnea. It entails wearing a mask that is connected to the PAP device which deliver pressure to the upper airway during sleep.

Other Name: CPAP

Sham Comparator: Lifestyle counseling

Device: Positive Pressure Therapy (PAP)

Positive pressure therapy is the standard of care for managing obstructive sleep apnea. It entails wearing a mask that is connected to the PAP device which deliver pressure to the upper airway during sleep.

Other Name: CPAP

Behavioral: LifeStyle Counseling

Subjects randomized to the lifestyle (and nutritional) counseling arm will be given advice on a balanced dietary and exercise plan.

Other Name: Dietary and Lifestyle Counseling

Detailed Description:

Type 2 diabetes mellitus is one of the most prevalent medical conditions, affecting a staggering 246 million people worldwide. Obstructive sleep apnea is a relatively common and often undiagnosed condition in the general population. Cross-sectional studies of clinic and population-based samples suggest that up to 40% of patients with obstructive sleep apnea have type 2 diabetes and up to 75% of patients with type 2 diabetes have obstructive sleep apnea. There is increasing evidence that the pathophysiological features of intermittent hypoxia and sleep fragmentation may be responsible for altering glucose homeostasis and worsening insulin sensitivity. The mechanisms through which obstructive sleep apnea impairs glucose metabolism are largely unknown. While intermittent hypoxemia and sleep fragmentation are likely to play an essential role, the relative contribution of each in the causal pathway remains to be determined. Moreover, whether the adverse effects of intermittent hypoxia and sleep fragmentation are mediated through an increase in sympathetic nervous system activity, alterations in corticotropic function, and/or systemic inflammation is not known. Furthermore, it remains to be determined whether positive pressure therapy for obstructive sleep apnea has salutary effects on glucose metabolism. Many of the available studies examining the effects of PAP on glucose tolerance and insulin sensitivity are plagued by small sample sizes, lack of a control group, and limited data on compliance with positive pressure therapy. The current study will assess, using a community-based sample, whether treatment of obstructive sleep apnea with positive pressure therapy will improve insulin sensitivity, as assessed by the frequently sample intravenous glucose tolerance test (primary outcome measure).

Eligibility

Ages Eligible for Study:

21 Years to 75 Years (Adult, Senior)

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

Ability to give informed consent

Obstructive sleep apnea (untreated)

Ability to comply with study-related assessments

Exclusion Criteria:

Inability to consent or commit to the required visits

Diabetes mellitus (fasting glucose > 126 mg/dl)

Use of insulin or oral hypoglycemic agent

Weight change of 10% in last six months

Use of oral steroids in the last six months

Severe pulmonary disease (i.e., COPD)

Renal or hepatic insufficiency

Recent MI or stroke (< 3 months)

Occupation as a commercial driver

Active substance use

Untreated thyroid disease

Pregnancy

Anemia (Hematocrit < 30%)

Any history of seizures or other neurologic disease

Poor sleep hygiene or sleep disorder other than sleep apnea

Excessive subjective sleepiness (Epworth score > 18)

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01503164